package com.lzl.utils;

import java.util.ArrayList;
import java.util.List;

public class Page<T> {
    //当前页码
    private Integer pageNo=1;
    //每页数量
    private Integer pageSize = 5;
    //总数据量
    private Integer totalCount = null;
    //总页数
    private Integer totalPageCount = 1;
    //分页数据集合，使用泛型兼容任意类型
    private List<T> data;

    public Integer getPageNo() {
        return pageNo;
    }

    public void setPageNo(Integer pageNo) {
        if(pageNo<=0){
            pageNo=1;
        }
        if(totalCount != null){
            if(totalPageCount >=1 && pageNo > totalPageCount){
                pageNo = totalPageCount;
            }
        }
        this.pageNo = pageNo;
    }

    public Integer getPageSize() {
        return pageSize;
    }

    public void setPageSize(Integer pageSize) {
        this.pageSize = pageSize;
    }

    public Integer getTotalCount() {
        return totalCount;
    }

    public void setTotalCount(Integer totalCount) {
        this.totalCount = totalCount;
        this.totalPageCount = this.totalCount % this.pageSize == 0 ? this.totalCount / this.pageSize : this.totalCount / this.pageSize + 1;
    }

    public Integer getTotalPageCount() {
        return totalPageCount;
    }

    public void setTotalPageCount(Integer totalPageCount) {
        this.totalPageCount = totalPageCount;
    }

    public List<T> getData() {
        return data;
    }

    public void setData(List<T> data) {
        this.data = data;
    }

    public int offset(){
        return (pageNo - 1) * pageSize;
    }
    //是否第一页
    public boolean isFirst(){
        return pageNo == 1;
    }
    //是否最后一页
    public boolean isLast(){
        return pageNo == totalPageCount;
    }
    //是否还有下一页
    public boolean hasNext(){
        return pageNo<totalPageCount;
    }
    //是否还有上一页
    public boolean hasPrevious(){
        return pageNo > 1;
    }
    //页面上显示指定长度的页码
    public List<Integer> getShowPageNos(int showCount){
        List<Integer> list = new ArrayList<Integer>();
        //先加中间页码
        list.add(pageNo);
        //每次页面计算的步长
        int step = 1;
        while (list.size() < showCount){
            boolean added = false;
            int left = pageNo - step;//左边减页码
            int right = pageNo + step;//右边加页码
            if(left >= 1){
                list.add(0,left);
                added = true;
            }
            if(right <= totalPageCount){
                list.add(right);
                added = true;
            }
            if(!added){
                break;
            }
            step++;
        }
        return list;
    }
}
